Back contact solar cell, cell module and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell, a cell assembly and a photovoltaic system. The back contact solar cell comprises a silicon wafer, the silicon wafer is provided with a front surface and a back surface which are oppositely arranged, the back surface comprises a first doped region, the first doped region is a P-type doped region or an N-type doped region, the first doped region is provided with a suede, the suede comprises a plurality of cone-like structures, each cone-like structure is provided with a conical surface and a conical top, and a concave part is formed at the joint of the adjacent cone-like structures; and the thickness of the first doping layer in the concave part is greater than the thickness of the first doping layer in the cone top. According to the back contact solar cell of the utility model, the thickness of the first doping layer at the concave part is greater than the thickness of the first doping layer at the cone top, so that the thickness distribution of the doping layers on the suede surface is more beneficial to the improvement of the cell efficiency.

Description

TECHNICAL FIELD

[0001] The utility model relates to solar cell technical field especially relates to a back contact solar cell, battery assembly and photovoltaic system. BACKGROUND

[0002] Solar cell is a kind of semiconductor device that can convert solar energy into electric energy, and photogenerated current is generated inside solar cell under light conditions, and electric energy is output through electrode.In recent years, solar cell production technology is continuously improved, production cost is continuously reduced, conversion efficiency is continuously improved, and solar cell power generation application is increasingly widespread and becomes important energy of electric power supply.Among them, back contact (Interdigitated back contact, IBC) solar cell, that is, interdigital back contact solar cell, positive / negative electrode grid lines are designed on the back of the cell, so that the front surface is completely avoided from the shielding of metal grid lines, and the optical loss caused by electrode grid lines shielding is eliminated, and the electrode grid lines can be designed wider than the existing, reduce series resistance loss, thereby greatly improve the conversion efficiency of the cell.

[0003] In the prior art, in order to reduce the reflectivity of the back surface incident light of the back contact solar cell, a cone-like structure is prepared on the doped region of the back surface of the back contact solar cell, and the doped region is a P-type doped region or an N-type doped region, so as to improve the double-sided rate of the cell and increase the power generation of the cell assembly.However, the thickness relationship of the doped layer in different regions of the doped region of the textured surface is not usually controlled, and the thickness distribution of the doped layer on the textured surface is not conducive to improving the efficiency of the cell, and there is still a problem of poor cell efficiency. UTILITY MODEL CONTENTS

[0004] The utility model provides a kind of back contact solar cell, to solve the problem of poor cell efficiency caused by the thickness distribution of the doped layer on the textured surface of the doped region of the back contact solar cell in the prior art.

[0005] The utility model is realized as follows: a kind of back contact solar cell is provided, comprising:

[0006] Silicon wafer, the silicon wafer has oppositely arranged front surface and back surface, the back surface includes first doped region, the first doped region is P-type doped region or N-type doped region, the first doped region is provided with textured surface, the textured surface includes a plurality of cone-like structures, the cone-like structure has cone surface and cone top, and adjacent cone-like structures form recess at junction.

[0007] First doped layer provided in the first doped region, the thickness of the first doped layer located in the recess is greater than the thickness of the first doped layer located in the cone top.

[0008] Preferably, the thickness of the first doped layer at the tip of the cone is greater than the thickness of the first doped layer at the face of the cone.

[0009] Preferably, the back surface comprises a second doped region, the second doped region being provided with the texturing; the back contact solar cell further comprises:

[0010] a second doped layer provided on the second doped region, the second doped layer being of opposite doping type to the first doped layer, the thickness of the second doped layer at the recess being greater than the thickness of the second doped layer at the tip of the cone.

[0011] Preferably, the thickness of the second doped layer at the tip of the cone is greater than the thickness of the second doped layer at the face of the cone.

[0012] Preferably, the first doped layer is one or a stack of at least two of a doped polysilicon layer, a doped amorphous silicon layer, and a doped microcrystalline silicon layer.

[0013] Preferably, the second doped layer is one or a stack of at least two of a doped polysilicon layer, a doped amorphous silicon layer, and a doped microcrystalline silicon layer.

[0014] Preferably, the first doped region is provided with at least two layers of the first doped layer stacked together, the thickness of each layer of the first doped layer at the recess being greater than the thickness of each layer of the first doped layer at the tip of the cone.

[0015] Preferably, the thickness of each layer of the first doped layer at the tip of the cone is greater than the thickness of each layer of the first doped layer at the face of the cone.

[0016] Preferably, the thickness of the first doped layer away from the silicon wafer is greater than the thickness of the first doped layer close to the silicon wafer.

[0017] Preferably, the back surface comprises a second doped region, the second doped region being provided with the texturing; the back contact solar cell further comprises:

[0018] a first passivation layer provided on the side of the first doped layer facing away from the silicon wafer, the thickness of the first passivation layer at the recess being greater than the thickness of the first passivation layer at the tip of the cone, and the thickness of the first passivation layer at the tip of the cone being greater than the thickness of the first passivation layer at the face of the cone.

[0019] Preferably, the back surface comprises a second doped region, the second doped region being provided with the texturing; the back contact solar cell further comprises:

[0020] a second passivation layer provided on the side of the second doped layer facing away from the silicon wafer, the thickness of the second passivation layer at the recess being greater than the thickness of the second passivation layer at the tip of the cone, and the thickness of the second passivation layer at the tip of the cone being greater than the thickness of the second passivation layer at the face of the cone.

[0021] Preferably, the back surface comprises a second doped region, the second doped region being provided with the texturing; the back contact solar cell further comprises:

[0022] A first tunneling layer between the first doped layer and the back surface, the first tunneling layer has a thickness at the recess greater than a thickness at the tip of the taper, and the first tunneling layer has a thickness at the tip of the taper greater than a thickness at the face of the taper.

[0023] Preferably, further comprising:

[0024] A second tunneling layer between the second doped layer and the back surface, the second tunneling layer has a thickness at the recess greater than a thickness at the tip of the taper, and the second tunneling layer has a thickness at the tip of the taper greater than a thickness at the face of the taper.

[0025] Preferably, a ratio of the thickness of the first doped layer at the recess to the thickness of the first doped layer at the tip of the taper is 1.2-1.8.

[0026] Preferably, a ratio of the thickness of the first doped layer at the tip of the taper to the thickness of the first doped layer at the face of the taper is 1.1-1.5.

[0027] Preferably, the tip of the taper is provided as a circular arc surface, the first doped layer is provided as a circular arc surface at the tip of the taper, and a curvature of the first doped layer at the tip of the taper is less than a curvature of the tip of the taper.

[0028] The utility model also provides a battery assembly, including above-mentioned solar cell.

[0029] The utility model also provides a photovoltaic system, including above-mentioned battery assembly.

[0030] The back contact solar cell provided by the utility model improves the double-side rate of the back contact solar cell by setting the rough surface composed of a plurality of conical body structures in the first doped area and reducing the reflectivity of the first doped area to the incident light on the back of the cell, thereby improving the power of the cell module composed of the back contact solar cell and increasing the power generation of the cell module; since the defect density of the conical top of the conical body structure is higher than the defect density of the recess at the intersection of the conical body structure, the thickness of the first doped layer at the recess is greater than the thickness of the first doped layer at the conical top, that is, the thickness of the first doped layer at the conical top is thinner than the thickness of the first doped layer at the recess, the first doped layer at the thinner conical top of the conical body structure can generate a stronger field effect, which is beneficial to reducing the recombination loss at the conical top, and the thickness relationship between the conical top and the recess of the first doped layer on the rough surface can well adapt to the uneven defect density distribution of the conical body structure of the rough surface, thereby effectively improving the cell efficiency; moreover, since the number of multiple reflections of the light at the conical top of the rough surface is greater than the number of multiple reflections of the light at the recess, the thickness of the first doped layer at the recess is greater than the thickness of the first doped layer at the conical top, which is beneficial to reducing the parasitic absorption side effect of the first doped layer and improving the light utilization rate, thereby improving the cell efficiency and making the cell efficiency better. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A structure schematic diagram of a back contact solar cell is provided for the utility model embodiment;

[0032] Figure 2 A structure schematic diagram of a silicon wafer of a back contact solar cell is provided for the utility model embodiment;

[0033] Figure 3 An SEM diagram of a first doped layer and a first passivation layer of a back contact solar cell on a rough surface of a first doped area is provided for the utility model embodiment;

[0034] Figure 4 An SEM diagram of a second doped layer and a second passivation layer of a back contact solar cell on a rough surface of a second doped area is provided for the utility model embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following further details the utility model by combining with the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the utility model and cannot be understood as limiting the utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the utility model and cannot be used to limit the utility model.

[0036] In the description of the utility model, it needs to understand that the orientation or position relation indicated by the terms "upper", "lower", "back", "front" and the like is based on the orientation or position relation shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.

[0037] In the utility model, unless otherwise expressly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0038] The following disclosure provides many different embodiments or examples for implementing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the utility model. In addition, the utility model can refer to the same reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed per se. In addition, the utility model provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0039] Please refer to Figures 1-3 The utility model provides a kind of back contact solar cell, comprising:

[0040] Silicon wafer 1, silicon wafer 1 has oppositely arranged front 2 and back 3, back 3 includes first doped area 31, first doped area 31 is P type doped area or N type doped area, first doped area 31 is provided with rough surface, and rough surface includes several conical structures 30, conical structure 30 has taper surface 301 and cone top 302, and adjacent conical structures meet to form recess 303;

[0041] First doped layer 4 is arranged in first doped area 31, and the thickness of first doped layer 4 located in recess 303 is greater than the thickness of first doped layer 4 located in cone top 302.

[0042] The utility model embodiment, the silicon wafer 1 includes opposite setting front 2 and back 3, the front 2 of silicon wafer 1 is the one side of back contact solar cell when working face to sunlight, the back 3 of silicon wafer 1 is the one side of back contact solar cell when working away from sunlight.

[0043] The utility model embodiment, first doped area 31 can be P type doped area, also can be N type doped area, when first doped area 31 can be P type doped area, then first doped layer 4 is P type doped layer, P type doped layer doped layer of doped with P type element, when first doped area 31 can be N type doped area, then first doped layer 4 is N type doped layer, N type doped layer doped layer of doped with N type element.

[0044] The utility model embodiment, first doped area 31 is provided with nappe, and the nappe includes a plurality of conoid structure 30, and the conoid structure 30 can be pyramid structure or conical structure. A plurality of conoid structure 30 array setting, adjacent conoid structure 30 can be spaced, also can partially overlap, wherein, when adjacent conoid structure 30 overlap, the junction of adjacent conoid structure 30 forms the recess 303 similar to V or U shape. Wherein, each conoid structure 30 includes conical surface 301 and cone top 302, and the cone top 302 is the highest point in conoid structure 30. In conoid structure 30, the conical surface 301 of conoid structure 30 is the collection of all sides of conoid structure 30, that is, all surfaces of conoid structure 30 except bottom and cone top 302. Wherein, the conoid structure 30 can be pyramid structure with three sides one bottom, or, the conoid structure 30 can be pyramid structure with four sides one bottom, or, the conoid structure 30 can be pyramid structure with five sides one bottom, or, the conoid structure 30 can be pyramid structure with six sides one bottom, of course, the conoid structure 30 can also be more quantity side and one bottom pyramid structure. Wherein, the top of conoid structure 30 can be set up sharply, also can be set up as arc surface.

[0045] The utility model discloses an embodiment, through being prepared by the first doped area 31 of the back of back contact solar cell's back 3 of a plurality of cone body structure 30 group's velvet, the first doped area 31 utilizes velvet to reduce the reflectivity of cell back 3 incident light, promotes the double -sided rate of back contact solar cell, thereby promotes the power of the back contact solar cell composition photovoltaic module, increases the power generation of photovoltaic module, and because the defect density of the cone top 302 of cone body structure 30 is higher than the defect density of the recess 303 of cone body structure 30 intersection, the thickness of the first doped layer 4 located recess 303 is greater than the thickness of the first doped layer 4 located cone top 302, that is, the thickness of the first doped layer 4 located cone top 302 is thinner than the thickness of the first doped layer 4 located recess 303, and the first doped layer 4 of the thinner position of the cone top 302 of cone body structure 30 can produce stronger field effect, which is conducive to reducing the recombination loss of the cone top 302 position, so that the thickness relationship of the first doped layer 4 at the cone top 302 position and the recess 303 position of the velvet can well adapt to the uneven defect density distribution of the cone body structure 30, thereby effectively improving the cell efficiency. In addition, because the number of multiple reflections of light at the cone top 302 position of the velvet is more than the recess 303 position, the thickness of the first doped layer 4 located recess 303 is greater than the thickness of the first doped layer 4 located cone top 302, which is conducive to reducing the parasitic absorption side effect of the first doped layer 4, improving the light utilization rate, and also improving the cell efficiency. The doping concentration of the first doped layer 4 located cone top 302 is greater than the doping concentration of the first doped layer 4 located recess 303, which is further conducive to the first doped layer 4 at the cone top 302 position of the cone body structure 30 producing stronger field effect.

[0046] In an embodiment of the utility model, the first doped layer 4 is one or a combination of a doped polysilicon layer, a doped amorphous silicon layer and a doped microcrystalline silicon layer. Preferably, the first doped layer 4 is a doped polysilicon layer.

[0047] In an embodiment of the utility model, the first doped layer 4 can be a single-layer structure or a stacked structure with two, three or more layers. When the first doped layer 4 is a stacked structure with at least two layers, a barrier layer 40 is arranged between the two adjacent first doped layers 4 to block electrode paste ablation and prevent the electrode paste from entering the silicon wafer 1. The barrier layer 40 can be one or a combination of silicon oxide, silicon nitride and silicon oxynitride. Figure 1 In the embodiment shown in the figure, the first doped layer 4 has two layers, and a barrier layer 40 is arranged between the two first doped layers 4.

[0048] In an embodiment of the utility model, the first doped area 31 is provided with at least two layers of first doped layers 4 stacked together, and the thickness of each first doped layer 4 located at the recess 303 is greater than the thickness of the first doped layer 4 located at the cone top 302.

[0049] In the embodiment, the first doped region 31 is provided with at least two layers of first doped layers 4 arranged in a stack, compared with the first doped layer 4 of a single-layer structure, the passivation effect of the first doped region 31 is improved, and the blocking ability of the film structure of the first doped region 31 to electrode paste ablation is improved, so that the electrode paste is prevented from burning through the film layer and entering the silicon wafer 1. In the case of the embodiment, the first doped region 31 is preferably a P-type doped region, and the first doped layer 4 is a P-type doped layer, so that the passivation effect of the P-type doped region is greatly improved, and the blocking ability of the first doped layer 4 of the P-type doped region to the electrode paste is improved.

[0050] As an embodiment of the utility model, the thickness of each first doped layer 4 at the cone top 302 is greater than the thickness of each first doped layer 4 at the conical surface 301.

[0051] In the embodiment, the thickness of each first doped layer 4 at the cone top 302 is greater than the thickness of each first doped layer 4 at the conical surface 301, which is beneficial to adapt to the problem of uneven defect density distribution of each first doped layer 4 of the conical structure 30, so that the battery efficiency can be effectively improved. Furthermore, it is beneficial to reduce the parasitic absorption side effect of each first doped layer 4, improve the light utilization rate, and improve the battery efficiency.

[0052] As an embodiment of the utility model, the thickness of the first doped layer 4 far from the silicon wafer 1 is greater than the thickness of the first doped layer 4 close to the silicon wafer 1.

[0053] In the embodiment, it can be understood that the thickness of the first doped layer 4 on the outside is greater than the thickness of the first doped layer 4 on the inside, so that the first doped layer 4 on the outside has better blocking ability to electrode paste ablation, and the ability of the first doped layer 4 to block the burning through of the metallization paste is improved.

[0054] As an embodiment of the utility model, the thickness of each first doped layer 4 at the cone top 302 is greater than the thickness of each first doped layer 4 at the conical surface 301.

[0055] In the embodiment of the utility model, the thickness of each first doped polysilicon layer at the recess 303 is greater than the thickness of each first doped layer 4 at the cone top 302, and the thickness of each first doped polysilicon layer at the cone top 302 is greater than the thickness of each first doped layer 4 at the conical surface 301, so that the thickness of each first doped layer 4 at the conical surface 301 is thinner than the thickness of each first doped layer 4 at the cone top 302. The parasitic absorption side effect of each first doped layer 4 at the conical surface 301 can be reduced, the light utilization rate is further improved, and the battery efficiency is improved.

[0056] In the embodiment of the utility model, the thickness of the first doped layer 4 in a certain part can be measured by a transmission electron microscope and the like, the thickness of the certain part can be the average thickness of the part directly measured, the thickness of the certain part can also be the average thickness obtained by measuring a plurality of points in the part, and the like, and the selection is made according to the measurability of the actual measurement target, and the thickness direction corresponding to the tangent at the position of the outer surface of the first doped layer 4 is perpendicular.

[0057] It can be understood that the thickness of the first doped layer 4 in the recess 303 can be the average thickness of the first doped layer 4 in the recess 303, the thickness of the first doped layer 4 in the cone top 302 is the average thickness of the first doped layer 4 in the cone top 302, and the average thickness of the first doped layer 4 in the recess 303 is greater than the average thickness of the first doped layer 4 in the cone top 302; or, the thickness of the first doped layer 4 in the recess 303 can be the thickness of the first doped layer 4 at any position in the recess 303, the thickness of the first doped layer 4 in the cone top 302 is the thickness of the first doped layer 4 at any position in the cone top 302, and the thickness of the first doped layer 4 at any position in the recess 303 is greater than the thickness of the first doped layer 4 at any position in the cone top 302.

[0058] As an embodiment of the utility model, the thickness of the first doped layer 4 in the cone top 302 is greater than the thickness of the first doped layer 4 in the conical surface 301.

[0059] In the embodiment, it can be understood that the thickness of the first doped layer 4 in the conical surface 301 is the average thickness of the first doped layer 4 in the conical surface 301, and the average thickness of the first doped layer 4 in the cone top 302 is greater than the average thickness of the first doped layer 4 in the conical surface 301; or, the thickness of the first doped layer 4 in the conical surface 301 is the thickness of the first doped layer 4 at any position in the conical surface 301, and the thickness of the first doped layer 4 at any position in the cone top 302 is greater than the thickness of the first doped layer 4 at any position in the conical surface 301.

[0060] In the embodiment of the utility model, the thickness of the first doped layer 4 in the recess 303 is greater than the thickness of the first doped layer 4 in the cone top 302, and the thickness of the first doped layer 4 in the cone top 302 is greater than the thickness of the first doped layer 4 in the conical surface 301, so that the thickness of the first doped layer 4 in the conical surface 301 is thinner than the thickness of the first doped layer 4 in the cone top 302, the parasitic absorption side effect of the first doped layer 4 in the conical surface 301 can be reduced, the light utilization rate is further improved, and the battery efficiency is improved.

[0061] As an embodiment of the utility model, the thickness of the first doped layer 4 in the conical surface 301 gradually decreases from the recess 303 to the cone top 302.

[0062] In the embodiment, since the defect density of the taper surface 301 is higher closer to the taper top 302, the thickness of the first doped layer 4 located on the taper surface 301 is gradually reduced from the concave portion 303 to the taper top 302, that is, the thickness of the first doped layer 4 located on the taper surface 301 is thinner closer to the taper top 302, the doping concentration of the first doped layer 4 located on the taper surface 301 is gradually increased from the concave portion 303 to the taper top 302, the field effect of the first doped layer 4 on the taper surface 301 is sequentially increased from the concave portion 303 to the taper top 302, and the thickness of the first doped layer 4 on the taper surface 301 is beneficial to adapt to the defect density distribution of the taper surface 301, thereby effectively improving the battery efficiency, and is also beneficial to reduce the parasitic absorption side effect of the first doped layer 4 on the taper surface 301 and improve the light utilization rate, thereby also improving the battery efficiency.

[0063] Please refer to Figure 1 , Figure 4 As an embodiment of the utility model, the back surface 3 comprises a second doped region 32, and the second doped region 32 is also provided with the above-mentioned textured surface; the back contact solar cell further comprises:

[0064] A second doped layer 5 is arranged in the second doped region 32, the doping type of the second doped layer 5 is opposite to that of the first doped layer, and the thickness of the second doped layer 5 located in the concave portion 303 is greater than the thickness of the second doped layer 5 located in the taper top 302.

[0065] In the embodiment, one of the first doped region 31 and the second doped region 32 is a P-type doped region, and the other is an N-type doped region. When the first doped region 31 is a P-type doped region, the second doped region 32 is an N-type doped region; when the first doped region 31 is an N-type doped region, the second doped region 32 is a P-type doped region.

[0066] As shown in Figure 4 , wherein the textured surface of the second doped region 32 and the textured surface of the first doped region 31 each comprise a plurality of conical body structures 30, the conical body structure 30 has a taper surface 301 and a taper top 302, and the adjacent conical body structures 30 form a concave portion 303 at the joint. Wherein the conical body structure 30 of the textured surface of the second doped region 32 and the conical body structure 30 of the textured surface of the first doped region 31 can be completely the same, or there can be differences. When the conical body structure 30 of the textured surface of the second doped region 32 and the conical body structure 30 of the textured surface of the first doped region 31 have differences, the differences can be in the vertex angle of the conical body structure 30. For example, the first doped region 31 is a P-type doped region, the second doped region 32 is an N-type doped region, the vertex angle of the conical body structure 30 of the textured surface of the first doped region 31 is greater than the vertex angle of the conical body structure 30 of the textured surface of the second doped region 32, so that the textured surface of the first doped region 31 is flatter than the textured surface of the second doped region 32, which is beneficial to improve the passivation effect of the P-type doped region and improve the battery efficiency.

[0067] In the embodiment of the utility model, the thickness of the second doped layer 5 in a certain part can be measured by a transmission electron microscope and the like, the thickness of the certain part can be the average thickness of the part directly measured, the thickness of the certain part can also be the average thickness measured by selecting multiple points in the part, and the like, which is selected according to the actual measurement target measurability and is not specifically limited. The direction of the thickness here is perpendicular to the tangent at the corresponding position of the outer surface of the second doped layer 5.

[0068] In the embodiment, the second doped region 32 is prepared by the plurality of conical body structures 30, the reflectivity of the incident light on the back surface 3 of the battery is reduced by the textured second doped region 32, the bifaciality of the back contact solar cell is further improved, the power of the back contact solar cell is improved, the power generation of the photovoltaic module is increased, the thickness of the second doped layer 5 at the concave part 303 is greater than the thickness of the second doped layer 5 at the cone top 302, that is, the thickness of the second doped layer 5 at the cone top 302 is thinner than the thickness of the second doped layer 5 at the concave part 303, the polycrystalline silicon at the cone top 302 of the conical body structure 30 is thinner, and a stronger field effect can be generated, which is beneficial to reducing the recombination loss at the cone top 302, the thickness of the second doped layer 5 at the cone top 302 of the textured surface and the thickness of the second doped layer 5 at the concave part 303 can be well adapted to the problem of uneven defect density distribution of the conical body structure 30, so that the battery efficiency can be effectively improved. Moreover, since the number of multiple reflections of light at the cone top 302 of the textured surface is greater than that at the concave part 303, the thickness of the second doped layer 5 at the concave part 303 is greater than the thickness of the second doped layer 5 at the cone top 302, which is beneficial to reducing the parasitic absorption side effect of the second doped layer 5 and improving the light utilization rate, so the battery efficiency can also be improved.

[0069] As an embodiment of the utility model, the thickness of the second doped layer 5 at the cone top 302 is greater than the thickness of the second doped layer 5 at the conical surface 301.

[0070] In the embodiment of the utility model, the thickness of the second doped layer 5 at the concave part 303 of the textured surface of the second doped region 32 is greater than the thickness of the second doped layer 5 at the cone top 302 of the textured surface of the second doped region 32, and the thickness of the second doped layer 5 at the cone top 302 of the textured surface of the second doped region 32 is greater than the thickness of the second doped layer 5 at the conical surface 301 of the textured surface of the second doped region 32, so that the thickness of the second doped layer 5 at the conical surface 301 is thinner than the thickness of the second doped layer 5 at the cone top 302, the parasitic absorption side effect of the second doped layer 5 at the conical surface 301 can be reduced, the light utilization rate is further improved, and the battery efficiency is improved.

[0071] As an embodiment of the utility model, the thickness of the second doped layer 5 at the conical surface 301 gradually decreases from the concave part 303 to the cone top 302.

[0072] In the embodiment, the thickness of the second doped layer 5 located on the conical surface 301 of the textured surface of the second doped region 32 gradually decreases from the concave part 303 to the conical top 302, that is, the second doped layer 5 on the conical surface 301 is thinner near the conical top 302, which is beneficial to adapt the thickness of the second doped layer 5 on the conical surface 301 to the defect density distribution of the conical surface 301, thereby effectively improving the cell efficiency, and is also beneficial to reduce the parasitic absorption side effect of the second doped layer 5 on the conical surface 301 and improve the light utilization rate, so the cell efficiency can also be improved.

[0073] As an embodiment of the utility model, the back contact solar cell further comprises:

[0074] The isolation region 33 is arranged between the first doped region 31 and the second doped region 32, and the isolation region 33 is provided with a textured surface or the isolation region 33 is provided as a polished surface.

[0075] In the embodiment, the first doped region 31 and / or the second doped region 32 are provided with a textured surface, and the surface of the isolation region 33 is provided as a polished surface, which can improve the passivation performance of the isolation region, so that the optical performance and passivation performance of the back surface 3 of the cell can be considered, the optical performance and passivation performance of the back surface 3 of the cell are balanced, and good conversion efficiency of the cell can be realized. When the isolation region 33 is provided with a textured surface, the anti-reflection effect of the incident light of the back surface 3 of the cell can be further improved.

[0076] As an embodiment of the utility model, the second doped layer 5 is one or a combination of a doped polysilicon layer, a doped amorphous silicon layer and a doped microcrystalline silicon layer. Preferably, the second doped layer 5 is a doped polysilicon layer.

[0077] In the embodiment of the utility model, the structure of the second doped layer 5 can be the same as that of the first doped layer 4, that is, it can be a single-layer structure, or a laminated structure with two, three or more layers. Among them, Figure 1 The first doped layer 4 is a laminated structure, and the second doped layer 5 is a single-layer structure.

[0078] In the embodiment of the utility model, the thickness of the first doped layer 4 at the concave part 303, the thickness of the first doped layer 4 at the cone top 302 and the thickness of the first doped layer 4 at the conical surface 301 can be flexibly set according to actual needs. For example, the thickness of the first doped layer 4 at the concave part 303 can be 350-500 nm; the thickness of the first doped layer 4 at the cone top 302 can be 300-460 nm, and the thickness of the first doped layer 4 at the conical surface 301 can be 200-400 nm. The thickness of the second doped layer 5 at the concave part 303, the thickness of the second doped layer 5 at the cone top 302 and the thickness of the second doped layer 5 at the conical surface 301 can also be flexibly set according to actual needs. For example, the thickness of the second doped layer 5 at the concave part 303 can be 300-450 nm; the thickness of the second doped layer 5 at the cone top 302 can be 250-350 nm, and the thickness of the second doped layer 5 at the conical surface 301 can be 180-230 nm.

[0079] As an embodiment of the utility model, the ratio of the thickness of the first doped layer 4 at the concave part 303 to the thickness of the first doped layer 4 at the cone top 302 is 1.2-1.8.

[0080] In the embodiment, the ratio of the thickness of the first doped layer 4 at the concave part 303 to the thickness of the first doped layer 4 at the cone top 302 is set to 1.2-1.8. Under this ratio range, the thickness of the first doped layer 4 at the cone top 302 and the thickness of the first doped layer 4 at the concave part 303 can be well adapted to the uneven defect density distribution problem of the conical structure 30, and the parasitic absorption side effect of the second doped layer 5 can be well reduced, and the light utilization rate can be improved.

[0081] For example, the ratio of the thickness of the first doped layer 4 at the concave part 303 to the thickness of the first doped layer 4 at the cone top 302 can be any value in 1.2, 1.25, 1.3, 1.5, 1.6, 1.7, 1.75 and 1.8.

[0082] As an embodiment of the utility model, the ratio of the thickness of the first doped layer 4 at the cone top 302 to the thickness of the first doped layer 4 at the conical surface 301 is 1.1-1.5.

[0083] In the embodiment, the ratio of the thickness of the first doped layer 4 at the cone top 302 to the thickness of the first doped layer 4 at the conical surface 301 is set to 1.1-1.5. Under this ratio range, the parasitic absorption side effect of the first doped layer 4 can be well reduced, and the light utilization rate can be improved.

[0084] Similarly, the ratio of the thickness of the second doped layer 5 located at the concave portion 303 to the thickness of the second doped layer 5 located at the cone top 302 can also be set to 1.2-1.8; the ratio of the thickness of the second doped layer 5 located at the cone top 302 to the thickness of the second doped layer 5 located at the cone surface 301 can also be set to 1.1-1.5.

[0085] For example, as shown in FIG. 2, the first doped layer 4 is a double-layer structure, the thicknesses of the two layers of the first doped layer 4 located at the concave portion 303 are 163 nm and 268 nm respectively, i.e. the thickness of the first doped layer 4 located at the concave portion 303 is 431 nm; the thicknesses of the two layers of the first doped layer 4 located at the cone top 302 are 149 nm and 206 nm respectively, i.e. the thickness of the first doped layer 4 located at the cone top 302 is 355 nm, and the thicknesses of the two layers of the first doped layer 4 located at the cone surface 301 are 86.5 nm and 175 nm respectively, i.e. the thickness of the first doped layer 4 located at the cone surface 301 is 261.5 nm. Figure 3 For example, as shown in FIG. 2, the second doped layer 5 is a single-layer structure, the thickness of the second doped layer 5 located at the concave portion 303 is 373 nm; the thickness of the second doped layer 5 located at the cone top 302 is 274 nm, and the thickness of the second doped layer 5 located at the cone surface 301 is 218 nm.

[0086] Figure 4 As an embodiment of the present application, the cone top 302 is provided in a circular arc surface, the first doped layer 4 located at the cone top 302 is provided in a circular arc surface, and the curvature of the first doped layer 4 located at the cone top 302 is smaller than the curvature of the cone top 302.

[0087] In this embodiment, the cone top 302 is provided in a circular arc surface, which can make the position of the cone top 302 smoother, and is beneficial to improve the passivation performance of the first doped region 31 at the position of the cone top 302; moreover, the curvature of the first doped layer 4 located at the cone top 302 is smaller than the curvature of the first doped layer 4 located at the cone top 302, which makes the position of the first doped layer 4 located at the cone top 302 flatter than the position of the cone top 302, and is beneficial to improve the passivation performance of the first doped layer 4 at the position of the cone top 302, and further beneficial to improve the battery efficiency.

[0088] Similarly, the first doped layer 4 located at the cone top 302 is provided in a circular arc surface, and the curvature of the first doped layer 4 located at the cone top 302 is smaller than the curvature of the first doped layer 4 located at the cone top 302, which is also beneficial to improve the passivation performance of the first doped layer 4 at the position of the cone top 302, and further beneficial to improve the battery efficiency.

[0089] As an embodiment of the present application, the cone top 302 is provided in a circular arc surface, the first doped layer 4 located at the cone top 302 is provided in a circular arc surface, and the curvature of the first doped layer 4 located at the cone top 302 is smaller than the curvature of the cone top 302.

[0090] As an embodiment of the present application, the cone top 302 is provided in a circular arc surface, the first doped layer 4 located at the cone top 302 is provided in a circular arc surface, and the curvature of the first doped layer 4 located at the cone top 302 is smaller than the curvature of the cone top 302.

[0091] ​The first passivation layer 6 is located on the side of the first doped layer 4 away from the silicon wafer 1, and the thickness of the first passivation layer 6 at the concave part 303 is greater than the thickness of the first passivation layer 6 at the cone top 302, and the thickness of the first passivation layer 6 at the cone top 302 is greater than the thickness of the first passivation layer 6 at the cone surface 301.

[0092] In the embodiment, when the first doped layer 4 is two or more layers, the first passivation layer 6 is located on the outer surface of the first doped layer 4 farthest from the silicon wafer 1.

[0093] In the embodiment, the first passivation layer 6 can further improve the passivation effect of the battery and improve the battery efficiency. Moreover, the thickness of the first passivation layer 6 at the concave part 303 is greater than the thickness of the first passivation layer 6 at the cone top 302, and the thickness of the first passivation layer 6 at the cone top 302 is greater than the thickness of the first passivation layer 6 at the cone surface 301. Since the adjacent adjacent positions of the conical structure 30 are relatively complex, the first passivation layer 6 at these concave parts 303 needs to be relatively thick to achieve a better passivation effect. Secondly, the cone top 302 of the conical structure 30 is more complex than the cone surface 301, so the thickness of the first passivation layer 6 at the cone top 302 is set to be thicker than the thickness of the first passivation layer 6 at the cone surface 301, which is conducive to the good matching of the passivation effect of each region of the conical structure 30 of the first doped region 31 and is conducive to improving the battery efficiency.

[0094] As an embodiment of the utility model, further include:

[0095] The second passivation layer 7 is located on the side of the second doped layer 5 away from the silicon wafer 1, and the thickness of the second passivation layer 7 at the concave part 303 is greater than the thickness of the second passivation layer 7 at the cone top 302, and the thickness of the second passivation layer 7 at the cone top 302 is greater than the thickness of the second passivation layer 7 at the cone surface 301.

[0096] In the embodiment, the first passivation layer 6 can further improve the passivation effect of the battery and improve the battery efficiency. Moreover, the thickness of the first passivation layer 6 at the concave part 303 is greater than the thickness of the first passivation layer 6 at the cone top 302, and the thickness of the first passivation layer 6 at the cone top 302 is greater than the thickness of the first passivation layer 6 at the cone surface 301. Since the adjacent adjacent positions of the conical structure 30 are relatively complex, the first passivation layer 6 at these concave parts 303 needs to be relatively thick to achieve a better passivation effect. Secondly, the cone top 302 of the conical structure 30 is more complex than the cone surface 301, so the thickness of the first passivation layer 6 at the cone top 302 is set to be thicker than the thickness of the first passivation layer 6 at the cone surface 301, which is conducive to the good matching of the passivation effect of each region of the conical structure 30 of the first doped region 31 and is conducive to improving the battery efficiency.

[0097] The first passivation layer 6 and the second passivation layer 7 are at least one or a combination of multiple of an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, a silicon carbide film layer and a silicon oxynitride film layer, and are not particularly limited herein.

[0098] As an embodiment of the utility model,

[0099] The first tunneling layer 8 is located between the first doped layer 4 and the back surface 3 of the silicon wafer 1, the thickness of the first tunneling layer 8 located in the concave part 303 is greater than the thickness of the first tunneling layer 8 located in the cone top 302, and the thickness of the first tunneling layer 8 located in the cone top 302 is greater than the thickness of the first tunneling layer 8 located in the conical surface 301.

[0100] In the embodiment, the first tunneling layer 8 can play a tunneling passivation role, further improving the battery passivation effect and the battery efficiency. Since the surface condition of the adjacent position of the conical structure 30 adjacent to the first doped region 31 is relatively complex, and the cone top 302 of the conical structure 30 is more complex than the conical surface 301, the thickness of the first tunneling layer 8 located in the concave part 303 is greater than the thickness of the first tunneling layer 8 located in the cone top 302, and the thickness of the first tunneling layer 8 located in the cone top 302 is greater than the thickness of the first tunneling layer 8 located in the conical surface 301. The thickness of the first tunneling layer 8 located in the cone top 302 is set to be thicker than the thickness of the first tunneling layer 8 located in the conical surface 301, which is conducive to the good matching of the tunneling passivation effect of the first tunneling layer 8 of the first doped region 31 to the conical structure 30, and is conducive to improving the battery efficiency.

[0101] As an embodiment of the utility model,

[0102] The second tunneling layer 9 is located between the second doped layer 5 and the back surface 3 of the silicon wafer 1, the thickness of the second tunneling layer 9 located in the concave part 303 is greater than the thickness of the second tunneling layer 9 located in the cone top 302, and the thickness of the second tunneling layer 9 located in the cone top 302 is greater than the thickness of the second tunneling layer 9 located in the conical surface 301.

[0103] In the embodiment, the second tunneling layer 9 can play a tunneling passivation role, further improving the battery passivation effect and the battery efficiency. Since the surface condition of the adjacent position of the conical structure 30 adjacent to the second doped region 32 is relatively complex, and the cone top 302 of the conical structure 30 is more complex than the conical surface 301, the thickness of the second tunneling layer 9 located in the concave part 303 is greater than the thickness of the second tunneling layer 9 located in the cone top 302, and the thickness of the second tunneling layer 9 located in the cone top 302 is greater than the thickness of the second tunneling layer 9 located in the conical surface 301. The thickness of the second tunneling layer 9 located in the cone top 302 is set to be thicker than the thickness of the second tunneling layer 9 located in the conical surface 301, which is conducive to the good matching of the tunneling passivation effect of the second tunneling layer 9 of the second doped region 32 to the conical structure 30, and is conducive to improving the battery efficiency.

[0104] The first tunneling layer 8 and the second tunneling layer 9 are at least one or a combination of multiple of an aluminum oxide film layer, a silicon oxide film layer and a silicon oxynitride film layer, and are not particularly limited herein.

[0105] As an embodiment of the utility model, further include:

[0106] The first electrode 10 contacts the first doped layer 4 through the first passivation layer 6.

[0107] The second electrode 11 contacts the second doped layer 5 through the second passivation layer 7.

[0108] In the embodiment, the polarity of the first electrode 10 and the second electrode 11 is opposite. For example, the first doped layer 4 is P type, and the first electrode 10 is positive; the second doped layer 5 is N type, and the second electrode 11 is negative.

[0109] The utility model embodiment further provides a battery assembly, the battery assembly includes the back contact solar cell of above-mentioned embodiment. It needs to be explained that, the battery assembly and above-mentioned back contact solar cell have same or similar beneficial effects, and the related places between the two can be mutually referred to, in order to avoid repetition, here will not be repeated.

[0110] In the embodiment, the plurality of back contact solar cells in the battery assembly can be sequentially connected together to form a battery string, thereby realizing the series connection of the current, for example, the connection of the battery pieces can be realized by setting the welding band (bus bar, interconnection strip), conductive back plate and the like.

[0111] It can be understood that, in such an embodiment, the battery assembly can further include a metal frame, a back plate, photovoltaic glass and a film. The film can be filled between the front and back surfaces of the back contact solar cell, photovoltaic glass, adjacent battery pieces and the like, and can be a transparent gel with good light transmission and aging resistance, for example, the film can be EVA film or POE film, which can be selected according to actual conditions, and is not limited here.

[0112] The photovoltaic glass can be covered on the film on the front surface of the back contact solar cell. The photovoltaic glass can be super white glass, which has high light transmittance, high transparency and excellent physical, mechanical and optical properties. For example, the light transmittance of the super white glass can be more than 92%, which can protect the back contact solar cell without affecting the efficiency of the back contact solar cell as much as possible. At the same time, the film can bond the photovoltaic glass and the back contact solar cell together, and the existence of the film can seal and insulate the back contact solar cell and prevent water and moisture.

[0113] The back plate can be attached to the adhesive film on the back of the back contact solar cell. The back plate can protect and support the back contact solar cell, has reliable insulation, water resistance and aging resistance, and the back plate can have multiple choices, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. The specific setting can be made according to the specific situation, which is not limited here. The whole composed of the back plate, the back contact solar cell, the adhesive film and the photovoltaic glass can be arranged on the metal frame. The metal frame serves as the main external support structure of the entire back contact solar cell module, and can stably support and install the back contact solar cell module. For example, the back contact solar cell module can be installed at the required installation position through the metal frame.

[0114] The utility model embodiment further provides a photovoltaic system, the photovoltaic system includes the battery module of above -mentioned embodiment. It needs to be explained that, the photovoltaic system has same or similar beneficial effect with above -mentioned back contact solar cell, and the correlation between both can be mutually referred to, in order to avoid repetition, here no longer tediously repeat.

[0115] In the embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus that generates electricity using solar energy, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that need to generate electricity using solar energy. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a current combiner box and an inverter. The photovoltaic array can be an array combination of a plurality of back contact solar cell modules. For example, a plurality of back contact solar cell modules can form a plurality of photovoltaic arrays. The photovoltaic arrays are connected to the current combiner box. The current combiner box can combine the currents generated by the photovoltaic arrays. The combined current flows through the inverter to convert into alternating current required by the power grid, and then is connected to the power network to realize solar power supply.

[0116] In the description of the present specification, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0117] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back contact solar cell, characterized by, Comprise: a silicon wafer having opposite front and back surfaces, the back surface comprising a first doped region, the first doped region being a P-type doped region or an N-type doped region, the first doped region being provided with a textured surface, the textured surface comprising a plurality of quasi-cone structures, each quasi-cone structure having a conical surface and a conical top, the quasi-cone structures being joined to each other at junctions to form concave portions; a first doped layer provided on the first doped region, the first doped layer having a thickness at the concave portions greater than a thickness at the conical tops.

2. The back contact solar cell of claim 1, wherein, the first doped layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

3. The back contact solar cell of claim 1, wherein, the back surface comprising a second doped region, the second doped region being provided with the textured surface; the back contact solar cell further comprising: a second doped layer provided on the second doped region, the second doped layer having a doping type opposite to that of the first doped layer, the second doped layer having a thickness at the concave portions greater than a thickness at the conical tops.

4. The back contact solar cell of claim 3, wherein, the second doped layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

5. The back contact solar cell of claim 1, wherein, the first doped layer being one or a stack of at least two of a doped polysilicon layer, a doped amorphous silicon layer, and a doped microcrystalline silicon layer.

6. The back contact solar cell of claim 3, wherein, the second doped layer being one or a stack of at least two of a doped polysilicon layer, a doped amorphous silicon layer, and a doped microcrystalline silicon layer.

7. The back contact solar cell of claim 1 wherein, the first doped region being provided with at least two layers of the first doped layer stacked on each other, each layer of the first doped layer having a thickness at the concave portions greater than a thickness at the conical tops.

8. The back contact solar cell of claim 7, wherein, each layer of the first doped layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

9. The back contact solar cell according to claim 7 or 8, characterized in that, a thickness of the first doped layer being greater away from the silicon wafer than close to the silicon wafer.

10. The back contact solar cell of claim 1 wherein, further comprising: a first passivation layer provided on a side of the first doped layer away from the silicon wafer, the first passivation layer having a thickness at the concave portions greater than a thickness at the conical tops, and the first passivation layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

11. The back contact solar cell of claim 3, wherein, further comprising: a second passivation layer provided on a side of the second doped layer away from the silicon wafer, the second passivation layer having a thickness at the concave portions greater than a thickness at the conical tops, and the second passivation layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

12. The back contact solar cell of claim 1 wherein, further comprising: a first tunneling layer provided between the first doped layer and the back surface, the first tunneling layer having a thickness at the concave portions greater than a thickness at the conical tops, and the first tunneling layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

13. The back contact solar cell of claim 3, wherein, further comprising: a second tunneling layer provided between the second doped layer and the back surface, the second tunneling layer having a thickness at the concave portions greater than a thickness at the conical tops, and the second tunneling layer having a thickness at the conical tops greater than a thickness at the conical surfaces.

14. The back contact solar cell of claim 1 wherein, The ratio of the thickness of the first doped layer at the concave part to the thickness of the first doped layer at the tip is 1.2-1.

8.

15. The back contact solar cell of claim 1 wherein, The ratio of the thickness of the first doped layer at the tip to the thickness of the first doped layer at the conical surface is 1.1-1.

5.

16. The back contact solar cell of claim 1 wherein, The tip is provided in a circular arc surface, the first doped layer at the tip is provided in a circular arc surface, and the curvature of the first doped layer at the tip is smaller than the curvature of the tip.

17. A battery assembly characterized by, A solar cell comprising any one of claims 1-16.

18. A photovoltaic system characterized by, A battery assembly comprising claim 17.

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